Synapse Analytics workspace can't access Data Lake Storage Gen2 container due to permissions error after RBAC update

Cloud Platforms Microsoft Azure
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1

We’re running into authorization issues with our Synapse Analytics workspace trying to access Data Lake Storage Gen2. The workspace was working fine until we reorganized our container structure and updated RBAC assignments. Now ETL pipelines are failing with AuthorizationPermissionMismatch errors.

The workspace uses a managed identity, and we’ve assigned Storage Blob Data Contributor role at the storage account level. However, we’re still seeing failures when trying to write processed data to specific containers. We also have ACL permissions set at the container level from our previous setup.


Error: AuthorizationPermissionMismatch
This request is not authorized to perform this operation using this permission.
RequestId: a7b3c4d5-e6f7-8901-a2b3-c4d5e6f78901

Not sure if this is a conflict between RBAC and ACL permissions or if the managed identity role assignment isn’t propagating correctly. Any guidance on the proper permission model for Data Lake Gen2 container access would be appreciated.

2

I checked the ACLs and found that several containers still have old service principal entries that are no longer valid. Before I start removing these, should I document the current state? Also, is there a way to test the managed identity access without breaking existing pipelines?

3

Let me provide a comprehensive solution addressing all three focus areas:

RBAC vs ACL Permissions: The root cause is the permission evaluation order. Azure checks RBAC first, then ACLs. When both exist, ACLs provide more granular control but can block RBAC permissions. For your scenario, the managed identity has RBAC permissions at the storage account level, but container-level ACLs without the identity’s object ID are blocking access.

Best practice: Use RBAC-only for new implementations. If you must use ACLs for legacy compatibility, ensure the managed identity’s object ID is included in all relevant ACL entries with rwx permissions.

Managed Identity Role Assignment: Verify the role assignment propagation:


az role assignment list --assignee <managed-identity-object-id> --scope /subscriptions/<sub-id>/resourceGroups/<rg>/providers/Microsoft.Storage/storageAccounts/<account-name>

Ensure the managed identity has Storage Blob Data Contributor role. Role assignments can take up to 5 minutes to propagate. If recently assigned, wait and retry.

Data Lake Gen2 Container Access: For immediate resolution:

  1. Get your Synapse workspace managed identity object ID from the Azure portal
  2. For each affected container, either remove ACLs entirely or add the managed identity:

az storage fs access set --acl "user:<object-id>:rwx" --path / --file-system <container> --account-name <storage>

Long-term solution:

  • Remove all ACLs from containers: `az storage fs access remove-recursive --acl default --path /
  • Rely solely on RBAC assignments at storage account level
  • Implement Azure Policy to audit/prevent ACL usage
  • Use custom RBAC roles if you need container-specific permissions

Migration Steps:

  1. Document current ACL configuration for rollback
  2. Create test container with RBAC-only, validate Synapse access
  3. For each production container: backup ACLs, remove them, test pipeline
  4. Monitor for 48 hours before moving to next container
  5. Implement Policy to enforce RBAC-only going forward

This approach resolves the immediate authorization errors while establishing a maintainable permission model. The key is understanding that RBAC provides sufficient granularity for most scenarios, and ACLs add complexity that’s rarely necessary with modern Azure services.

4

You can use Azure Storage Explorer or Azure CLI to check ACLs. With CLI, use:


az storage fs access show --path / --file-system <container-name> --account-name <storage-account>

This will show you the ACL entries for the container root. For a comprehensive solution, I’d recommend moving to RBAC-only permissions. Data Lake Gen2 supports RBAC fully now, and it’s much easier to manage at scale than maintaining ACLs across multiple containers. You can disable ACL inheritance and rely solely on RBAC assignments at the appropriate scope level.

5

Definitely document everything first. For testing, create a test container with RBAC-only permissions and run a simple Synapse notebook to read/write to it using the managed identity. This validates your RBAC setup without touching production containers. Once confirmed working, you can systematically migrate containers one at a time during maintenance windows. Also consider implementing Azure Policy to prevent ACLs from being set in the future if you’re going RBAC-only.

6

Thanks for the quick response. So if I understand correctly, the ACLs we set earlier are blocking access even though RBAC should grant it? How do I check what ACLs are currently set on the containers? We have about 15 containers and I’m not sure which ones have custom ACLs applied.